Cage nuts (also known as cage nut assemblies) are used to bolt two structures together. The cage nut contains a threaded nut. The threaded nut is enclosed by a cage. The cage nut is attached, such as by welding, to the rear of a first structure. The nut does not freely rotate within its cage. As a result, the first structure is provided with threads into which a bolt may be tightened. A second structure is positioned adjacent to the first structure such that a bolt may simultaneously extend through an opening within each structure and the threads of the nut. The bolt is tightened to secure the structures together. Cage nuts are useful in providing a fixed threaded base in an area which is difficult to access. For example, a cage nut may be attached to the interior surface of an enclosed automobile door pillar. Cage nuts are also used to speed the assembly of two previously fabricated subassemblies together. One subassembly has a cage nut attached to it. The second subassembly may be quickly attached to the first subassembly with a bolt.
In addition to providing threads for attachment to a bolt, a cage nut also provides for the variable or floating positioning of the nut. Often a nut is needed in an inaccessible location and the nut must be able to be repositioned prior to its attachment to a bolt. The automobile door pillar previously described is such an example. Not only are threads needed on the interior of the door pillar, the threads must be repositionable. After a door and a hinge are attached to a door pillar with a bolt and a cage nut, the door must be aligned with the automobile body. Cage nuts allow the door to be moved into an aligned position because the nut may move, or be repositioned, within the cage. After appropriate alignment between the door on the automobile body is obtained, the bolt is tightened into the nut to maintain the alignment. Typically, a plurality of cage nuts are used to attach a door to a door pillar.
A typical prior art cage nut has a cage comprising three walls covered by a plate. The walls form a three sided rectangular enclosure. The fourth side does not have a wall. Rather, a bendable tab extends from the plate to retain a nut and a flange within the enclosure. The plate is at the exit end of the enclosure. The other end is the entrance end. The entrance end is where a bolt enters. Thus, the exit end may be referred to as the bottom of a cage nut assembly. The nut and the flange are fixed together. The flange and the walls are configured so that the nut and the flange may move within the cage structure, but rotation of the flange is limited by contact with one or more of the walls so that the bolt may be tightened into the nut.
Several problems are associated with the design of prior art cage nut assemblies. If the flange and the nut need to be removed from the cage after installation upon a structure, the flange and the nut may only be removed through the wall opening where the bendable tab extends. The bendable tab is bent out of the way and the nut and flange are removed laterally from the cage. The nut and the flange are not removable through the bottom of the cage because removal is prevented by the plate. One of the functions of the plate is to retain the nut and the flange within the cage. Therefore, the orientation of the cage nut assembly upon a limited access structure may be limited to an orientation which permits lateral removal of the nut and the flange through the open wall without interference. Since the cage is comprised of three walls and an open wall forming a cage structure the amount of torque which may be applied to the nut and the flange is limited. A three walled rectangular structure with a fourth open wall will fail with a lower degree of bolt torque than a four walled rectangular structure. Another problem is the amount of nut and flange surface area which contacts the plate and walls of the cage. If the cage nut assembly is mounted so that the plate prevents the flange and the nut from falling out of the cage due to gravity, a large portion of the nut and flange bottom surface will be in contact with the plate. Other mounting positions of the cage nut assembly may result in side surfaces of the flange being held in contact with one of the walls of the cage by gravity. It is not uncommon for a cage nut assembly to be subjected to a paint process or an electrocoating process after attachment to a structure. These processes are usually directed at the structure itself and are incidentally applied to the cage nut assembly. The process may involve post process baking such as paint baking. As a result, the nut and the flange become fixed to the cage. When the nut and flange are fixed to the cage, variable positioning of the nut and the flange are lost. The bond between the nut and the flange and the cage must then be broken in order to reachieve the variable positioning of the nut and the flange within the cage. This consumes manufacturing time.
A cage nut assembly is needed which would have the following features. Its cage would have four walls forming a four sided enclosure. This would increase the maximum torque which may be applied to the nut. The nut and the flange would be removable through the bottom of the cage. This would allow the cage nut assembly to be oriented in many more positions within a confined assembly area, such as a door pillar. The position of the open wall for lateral removal of the nut and the flange would no longer be a factor. The nut and the flange would be suspended within the cage, rather than resting upon the cage structure. This would minimize the tendency of the nut and the flange to be welded to the cage by paint or electrocoating material.
The improved cage nut assembly described herein satisfies these needs.